Online communities have become an essential component in the current society, and the sense of virtual community (SOVC) plays a determinant role in affecting the community's sustainability. Thus, understanding the predictors of SOVC is a topic of interest for both researchers and practitioners. To do so, we take a relational approach and propose a dual-process model in which one-to-one online social interactions facilitate the development of SOVC through the accumulation of two types of social capital. Drawing on a survey of 624 members of an interest-based SNS in China, the findings indicated that both public and private online social interactions influence SOVC, but through different pathways. Specifically, the impact of public interactions on SOVC is mediated by both bridging and bonding social capital, and the mediation effect of bridging is stronger than that of bonding. Meanwhile, the association between private interactions and SOVC is completely mediated by bonding social capital. This study contributes to the SOVC scholarship by identifying the importance of one-to-one online social interactions and explicating the underlying mechanism. Implications of the findings and directions for future research are discussed.